In a chromatograph, such as a GC or LC, sample components which have been temporally separated by a column are detected with an ultraviolet visible spectrometer or similar detector, and a chromatogram showing a temporal change in the signal intensity is created based on the detection signals.
In order to perform a qualitative or quantitative analysis of various components contained in a sample, it is necessary to locate a peak included in the obtained chromatogram. Normally, the peak is automatically detected from the chromatogram by an automatic detection algorithm (for example, see Patent Literature 1).
However, performing an automatic detection of a peak is not always appropriate. For example, if a plurality of components overlapping each other at close points in time are eluted from the column, a plurality of peaks overlapping each other appear on the chromatogram. In such a case, it is impossible to accurately detect each individual peak since the beginning or ending point of each peak is unclear. Besides, if the amount of target component is much smaller than those of the other components, the peak of the target component will be obscured by other peaks and the detection accuracy of that peak will be lowered. Furthermore, in the case of a temperature-programmed analysis in which the column temperature is gradually increased, or a gradient analysis in which the analysis is performed using a mixture of mobile phases with their mixture ratio gradually changed, the baseline of the chromatogram changes with the passage of time (i.e. drift of the baseline occurs), making it difficult to accurately detect the peak by automatic detection. Accordingly, conventional devices have the function of allowing operators to manually enter the peak-beginning point, peak-ending point and/or similar information for locating the peak position, to enable the detection of the peak (and baseline).